Electromagnetic apparatus



April 12, 1932.

F. C. M. STORCH ELECTROMAGNETIC APPARATUS Filed Sept. 2l.

1929 2 Sheets-Sheet, l

@IQQQQ April l2, 1932. F. c. M.. sToRcH ELECTROMAGNETIC APPARATUS 2' sweets-sheet 2 Filed Sept. 21, 1929 Patented Apr. 12 1932 UNITED STATES PATENT OFFICE ELECTROMAGNETIC APPARATUS Application led September 2l, 1929, Serial No. 394,307, and in Germany September 25, 1928.

This invention relates broadly to that kind of electromagnetic devices which are provided With exposed pole surfaces and are employed for moving and mounting pieces of 6 Work for instance in connection with machine tools and the like, for the separation and removal of magnetic material from unmagnetic substances, such as for instance insulating material, food, textile material and l the like, and for various other uses. Inasmuch as the eiiiciency of devices of the kind referred to depends largely upon the extent and the distribution of the exterior', usually exposed pole surface and the prevention of arcing between the different outer sections thereof it has been suggested to subdivide the available pole surface by means o'f diamagneticor insulating material. There was the diiiiculty however that by the electric or thermic conductivity of this separating diamagneticor insulating material the poleshoes were most unfavorably affected and it was not possible to interrupt the magnetic action with the promptness required for the purpose of removing ieces of work from machine tools or of quickly removing the magnetic material extracted from food, textile fibres and the, like. rlhese causes and the rather considerable differences of the coefficients of expansion of the poles and of the diamagnetic or insulating material gave rise to the formation of Cracks and the disassembling of the parts, so that dirt, water, oil and other substances used in the treatment of articles on machine tools and the like could easily find their way to the magnets and the exciting spools themselves. p

Now, it is one of the main objects of my invention to eliminate these difficulties, and furthermore to highly increase the efficiency and Simplify the construction of machines and devices of the general kind referred to and to accomplish other important results and advantages which will appear from the following specification and from an inspection of the drawings. i

The invention will be more fully described by reference to the accompanying drawings, showing by way of exemplification some forms of embodiment of the principles of my invention. In the drawings Figure 1 is a i vertical longitudinal section through a magneto-electric apparatus of the kind referred to on the line I-I of Figure 2. In Figure 2 I have shown a top plan view of the embodiment of Figure 1 seen in the direction of the arrow on the line II--II of Figure 1, and Figure 3 is a transverse section on the line III-III of Figure'2. In Fi ures 4 and 4a one of the electro-magnetic e ements of the device is shown respectively in side View and in top plan view. Figure 5 is a longitudinal section of a modified form of construction of the apparatus according to this invention. Figure 6 is a longitudinal section on the line 65 VI-VI of Figure 5 and at right angle thereto. Figure 7 is a modified construction of a magnet-core. Figure 8 shows the ,arrangement of the exciting coils for this modification of Figure 7. Figures 9 and 11 are sec- 70 tional views of a modified detail of the pole shoes, and Figure 10 is a plan View corresponding to Figure 11.

The invention is broadly distinguished by the fact that a very large number of elect-romagnetic elements or units 8, 9 may be arrangedin any suitable frame, casing 3 or the like and upon a bed plate 5 in such a manner that any desired number of units may be easily added and connected to the aggregate 30 or detached therefrom according to requirements, and moreover, by the fact that for the insulation of the pole-pieces only such insulating material is used which is of rough, and preferably brous texture, as eontradistinguished from smooth texture, and of nonmetallic, absolutely unconducting character, such as asbestos, infusorial earth or the like, preferably in combination with some kind of unconducting non-metallic thermo-plastic binding agent, and by the fact that the total Y amount and acting surface of such insulating material between the pole shoes is large-ly in excess of the acting surface of the body of the pole shoes, so that the acting surface of the device of this invention comprises a large number of' pole shoes on a comparatively restricted area and alternating with a large excess of acting surface of insulating material l v between the pole shoes, and possessing a very high degree ofwretaining, frictional and adhering properties. Thus, instead of interrupting theadhesive surface of the magnets and of their lines of force, the arrangement of the insulating material of this invention highly increases these valuable properties of the magnet poles and may even constitute the main portion of the active surfaces in which the magnet poles are distributed and subdivided.

yThe units or elements comprise for inl' stance fiattened magnets 8 of soft iron core or composed of aplurality of superimposed thin, so-called dynamo-sheets of metal and surrounded by a substantially rectangular exciting coil 9. In the transverse direction of the device the coils 9 alternate with intermediate magnets, constitutin the opposite poles. The magnets are provi ed with a large amount of outwardly projecting pole shoes 2. Between these pole shoes 2 the insulating material is disposed which consists of fibrous inorganic material which possesses a high degree of frictional capacity, for instance asbestos, steatite and the like and preferably mixed with a highly insulating binding agent, such as resin or bakelite or the like, or similar artificial resins. Instead thereof kiesel ur or other material may be used which o ers a high frictional resistance or coeflicient of adhesion with relation to the work which is caused to be engaged by the acting surface of the device. Other binding agents may also be used in connection with the asbestos,'kieselgur or the like, provided they are non-hygroscopic and dol not act chemically upon the metal of they magnets and magnet poles and will not interfere with the adhering qualities of the asbestos and ofJ equivalent insulating material.

The magnets are preferably arranged in a frame or casing 3 and are secured in position by threaded shafts or the like 6 axially paralvlel therewith and threadedly secured in the insulating material 1. A preferred-way of securing the parts in position is by forcing the magnets with their poles 2 into a'sufiicient supply of still plastic, unmoulded insulating material 1 by tightening the nuts 6. For this purpose the pole shoes 2 ma constitute ordinary screw bolts having pointed ends adapted to penetrate through the insulating material whichis thereby highly compressed.

In order to impart the necessary rigidity to those parts of the device which are penetrated by the screws 6, the outer portion of the frame work 1,v serving for the reception of the screws may be composed in part or wholly of wood, zinc, or the like. The pointed ends of the magnets are cut off or ground down when the entire surface is' finished. 7 are shoulders in the vbottom plate for securing the magnets in position.

In Figures 5 and 6 Ihave shown the application of the principles of my invention'to the construction of a circular or polygonal drum shaped magnetic separator for removing particles of iron from articles of food, coffee or the like, cereals, flax, bales of cotton, paper, insulating material and the like which shoes of the magnets. In this modificatidn of the device the magnets are housed u on the outer cylindrical drum-like surface o 'a core 12 of iron or the like mounted upon the hollow shaft 10, or the magnets may be disposed in corresponding cylindrical or otherwise shaped sockets or depressions of the drum with their pole-shoes v2 'projectin from the surface of the drum and embed ed or 'surrounded by the insulating material 1. The

4hollow shaft 10 is mounted upon the stationary shaft 19 which may carry the means for the admission of the exciting current which is caused to enter the magnets by lWay of the niake-and-break contacts 20,21 secured to the base plate 11. With coarsely granular material it is of advantage to have the ends of the l pole shoes. 2 project somewhat, while in the case of more finely comminuted material to be submitted to the de-ironing operation this is not necessary, the pole shoes in this case being flush with the outer' surface of the ilisulating material 1. The plates or sections of this insulating mateniall may be .secured in position on the core 12 by means of clamping plates or fish-plates 17 mounted on t e screws 18. While I have'shown the different outer sections of thel drum to constitute thel side of a polygon, I wish it to be understood that the drum may also vbe of circular or elliptical or other suitable shape, but I prefer the polygonal configuration in combination with the projecting pole shoes particularly in the case of relatively coarsely comminuted material.

In Figure 7 I have shown a configuration of magnet core, substantially comprising a three-legged lfork and which is particularly adapted for use in ,connection with alternat' ing current, but it is obvious that this form' of core may likewise be employed in connection with direct current, and instead of. carrying coils on each of its legs', it may also be so arranged as to carry coil'son its central leg only.

The great subdivision and distribution of the pole shoes, so to speak, throughout the insulating mass of material may be further increased by providing a depression or socket in the heads of the pole shoes, as shown for instance in Figures 9,10 and 11 of the drawings. In these figures 13 and 15 indicate the pole shoes and 14 the socket or cavity therein which is filled with the insulating material 2. By this means both the insulating as well as the metallic magnetic active sur aces are F- increased and the adhering and holding ca' pacity of the device is accordinglly- 1ike- Wise considerably augmented. 15 in are caused to pass in contact with the pole 'zo 1GoY its I igures lles 10 and 11 is a hexagonal nut, such as are used for instance for the purpose of holdin the outer plate of the device in position. uch nuts 15 or circular nuts may be screwed at 16 onto the ends of the magnets and thereby constitute the heads and pole shoes thereof, and by tightening said nuts 13, 15 the cover plate 1, 2 can be very securely and tightly fastened upon the magnets, so as to be absolutely safe against leakage and loosening of the parts.

The very high degree of subdivision of the magnetic surface and the factthat the insulating material possesses a high degree of resistibilityagainst electric and thermic influences and has moreover a coefficient of expansion similar to that of the pole shoes and the most intimate interlocking engagement of the parts obtained by this subdivision and by the fibrous or somewhat finely granular condition of the insulating material which is preferably in excess of the magnetic outer surface are instrumental in preventing leaks and fissures and in insuring a perfectl solid continuous outer active surface, and tiere is no danger of shrinkage at the points of contact of the two kinds of active surfaces.

It is obvious that the magnets and pole shoes may have any desired cross-sectional shape, circular, cornered, quadrangular, ellipsoidal and other shape, and in view of the increased flow of lines of force the adhering and braking properties of the insulating material' are reatly increased.

It may e noted that in a preferred construction the coils may be wound in such a manner that their individual voltage is below the working voltage. This fact greatly contributes to the lengthening of the life of the several coils and of the entire apparatus.

The casing 3 may be of sufficiently strong zinc plates. It thereby becomes articularly adapted for the protection against atmospheric influences and for tbe application of putty or other'tightening agents.

As a material for`the insulating packing I may use the commercial product known as Ferodo, and comprising a tissue made from inor anic fibrous material and containing arti cial phenolic resins or the like or 'an unwoven mixture thereof with said fibrous substances and particularly distinguished by its frictional resistance.

In devices constructed according to my invention there .is a substantial absence of remanent magnetism which would interfere with the necessary abrupt interruption of the magnetic fiow,or of eddy currents in the case of alternate current being used, so that the desired mechanical holding and retaining properties are not interfered with. f

Other fibrous material besides that above mentioned, such as different kinds of wood may also be used provided itis free yfrom hygroscopic properties, and preferably in and comprising a mixture of fibrous, iexible inorganic substances with athermoplastic binding agent.

2. In an electromagnetic chuck in combination, a plurality of electromagnets, a plu- "rality of parallel, spacedly disposed and substantially equally projecting ole-pieces at corresponding ends of each ofp said electromagnets, and an insulating packing between said pole pieces and `adhering thereto and substantially flush with the end-faces thereof, and comprising a mixture of fibrous asbestos and a thermoplastic resinous binding agent.

3. In an electromagnetic chuck the combination with a drum-shaped housing and a plurality of substantially radially is osed rows of electromagnets in the perip eral portion of said housing, of an outer, prismatic, cross-sectionally polygonal insulating casing, comprising a compound of inorganic fibrous material and a thermoplastic binder secured to said housing and closely engaging the same, and pole-pieces on said electromagnets permeating the fiat sides of the insulating casing.

4. In an electromagnetic chuck the combination with a drum-shaped housin and a plurality of substantially radially is osed rows of electromagnets in the perip eral portions of said housing, of an outer hollow,

prismatic and cross-sectionally polygonal insulating casing, angularly `projecting between tlie electromagnets and'secured to the housing and closely engaging the same andy comprising an insulating mixture of fibrous asbestos with a thermoplastic resinous binding agent, and substantially radially disposed pole pieces on said electromagnets prof jecting therefrom and permeating the flat sides of said insulating casing.

FRIEDRICH CONRAD MARTIN STORCII.

ICI) 

